Kinetic analysis of additive on plasma electrolytic boriding

Abstract

Plasma electrolytic boriding (PEB) is a method of combination surface strengthening and surface texturing on metal. In this study, the kinetics and the lubrication friction of borided layers in the plasma electrolytic boriding on the Q235 were investigated in an aqueous solution for 5-15 min. The cross-section and surface morphologies of the boriding layers were confirmed using scanning electron microscope (SEM). The presence of phases on the surface was determined using the X-ray diffraction. The hardness and the lubrication friction were evaluated using a micro-hardness tester and pin-on-disk friction tester in an oil sliding condition, respectively. The PEB layer contains phases in FeB, Fe 2 B, Ni 3 B 4 , NiB, and Ni 2 B. It is indicated that the value of activation energy in the PEB treatment is approximately 186.17 kJ/mol. The random micro-pores in surface texturing are unevenly distributed on the surface of the Q235. The micro-hardness of the boriding layer is up to 900 HV, whereas that of the substrate is approximately 181 HV. The weight loss of PEB sample in 10 min is 0.0017 mg in the lubrication friction, whereas that of untreated sample is 0.0047 mg in the same condition. The formation of boriding strengthening surface texturing in PEB improves lubrication friction greatly.